Oscillators generate clocking signals in electronic circuits. The frequency of a signal generated by an oscillator can be either fixed at a certain value or controlled by another parameter such as a voltage.
Oscillators can be of various configurations, such as the push-push oscillator. In this configuration, 2 transistors are typically made to oscillate by the addition of other electronic elements. Each of the 2 oscillating circuits thus formed oscillate at the same frequency but with a 180.degree. phase difference.
One example of such an oscillator scheme is illustrated in FIG. 1. Each of the 2 oscillators (G and H) is formed by a transistor (S), a varactor diode (X), and an inductor (C). The values of these elements are chosen such that each oscillator produces a signal of frequency f.sub.o. An embedding element, such as a capacitor (A) or a dielectric resonator, is added between the transistors (S). If bipolar, npn transistors are used, the embedding element is connected between the emitters of the transistors. If MESFET's are used, the embedding element connects between the transistors ' sources. This embedding element causes the 2 oscillators (G and H) to oscillate with a 180.degree. phase difference thus causing the oscillator scheme to produce a signal of 2f.sub.o.
Another example of a prior art oscillator scheme is illustrated in FIG. 2. In this scheme, 2 oscillators (Y and Z), each formed by a transistor (R), a capacitor (O), and an inductor (T), oscillate at a frequency f.sub.o. A d.c. connection is formed between the transistors by connecting the transistors ' sources through the inductors (p). The common point between the inductors connects to a current source (U). The resulting output signal from this oscillator, with a frequency of 2f.sub.o, is the sum of the spurious signals from the 2 oscillating circuits (Y and Z).
These push-push oscillators, however, are not practical in certain applications because of their limited output power. Also, these schemes often allow the noise from the power supply to pass through to the output signal. In addition, the output signal of the second method will be unstable since it is the result of spurious oscillations and, therefore, there is no guarantee that the spurious oscillations will be present when required.
There exists a need, therefore, for a push-push oscillator having a stable output frequency, lower noise amplitude, and a higher power output.